Apparatus for discharging molten metals with pump emptying means

ABSTRACT

Apparatus for discharging molten metal, such as lead, has a pump demountable from a support member attached to a melting pot, the pump, support member and a ducted block, also mounted on the support member, having cooperating upwardly inclined passages for the flow of the molten metal and terminating in a discharge opening or nozzle. The ducted block and nozzle (where present) are provided with auxiliary heating.

United States Patent [1 1 Stamp [4 1 Apr. 2, 1974 APPARATUS FORDISCHARGING MOLTEN METALS WITH PUMP EMPTYING MEANS [76] Inventor: ThomasBlackledge Stamp, Silvretta,

Langley Rd., Winchcombe, Gloucestershire, England [22] Filed: Sept. 20,1972 [2]] Appl. No.: 290,748

[30] Foreign Application Priority Data Sept. 24, 1971 Great Britain44543/71 [52] U.S. Cl. 222/146 I-IE [51] Int. Cl B22d 37/00 [58] Field0t Search 222/385, 146 HE, DIG. 10, 222/DIG. 1; 164/316, 318; 417/434,446

[56] References Cited UNITED STATES PATENTS 2,520,348 8/1950 Tama222/DIG. 1O l,238,l08 8/1917 Cole 222/DIG. 10

3,396,873 8/1968 Nef 222/DIG. l 3,652,073 3/l972 Lewis 266/38 FOREIGNPATENTS OR APPLICATIONS l,l5l,357 7/1963 Germany 222/385 900,842 7/1945France l64/3l8 Primary ExaminerRobert B. Reeves Assistant ExaminerDavidA. Scherbel Attorney, Agent, or Firm-Young and Thompson [5 7] ABSTRACTApparatus for discharging molten metal, such as lead, has a pumpdemountable from a support member attached to amelting pot, the pump,support member and a ducted block, also mounted on the support member,having cooperating upwardly inclined passages for the flow of the moltenmetal and terminating in a discharge opening or nozzle. The ducted blockand nozzle (where present) are provided with auxiliary heating.

14 Claims, 4 Drawing Figures 7 PATENTEDAPR 21974 3800 986 SHEET 2 BF 233 33 FIG. 2.

APPARATUS FOR DISCHARGING MOLTEN METALS WITH PUMP EMPTYING MEANS Thisinvention relates to lead pouring or metering systems as used in leadcasting machines and is particularly, though not exclusively, applicableto a lead pouring system for use in a casting machine for casting platesor parts of lead accumulators, comprising a single fixed mould, or aseries of moulds mounted on an endless conveyor to be brought insequence below a pouring outlet of the system. In such machines it isimportant the quantity of molten metal delivered to each mould shall befairly accurately controlled and many attempts have been made to designpouring systems which will operate continuously without frequentmaintenance.

One such system includes a continuously operating pump supplying moltenlead from a melting pot through a long delivery pipe, which isexternally heated electrically or by gas, to a pouring ladle from whicha continuous overflow or return passage leads back to the melting pot.At appropriate times the ladle is tilted to discharge a metered quantityinto a mould. This system has many disadvantages: the molten surface isexposed to air over a large area and is very subject to oxidisation; thevelocity of discharge is quite high and uncontrolled and spillage mayoccur; the metal is ,continuously being supplied to and returned fromthe ladle so that large heating equipment is necessary to prevent thetemperature dropping excessively; and, in the event of any breakdown ofthe equipment, the whole system has to be shut down and, in some cases,it may even be necessary for the molten metal drained off from thecontainer before the pump can be removed for maintenance.

Accordingly it is an object of the present invention to provide animproved metal pouring system which will be less susceptible to theseexisting problems and disadvantages.

Broadly stated, the invention consists in apparatus for pouring ormetering the discharge ofa molten metal such as lead, comprising amelting pot or container provided with heatingmeans to maintain themetal in a molten state, a pump mounted at least partly within thecontainer with its inlet near the bottom of the container, the pumpbeing physically mounted on a support member connected to or formingpart of the container, a discharge passage from the support member and apump passage in the pump cooperating to provide a path for the dischargeof molten metal from the pump to a discharge nozzle or opening so thatthe pump can be readily demounted from the support member formaintenance or replacement.

Preferably the pump is a reciprocating piston or plunger pump actuatedby a fluid operated ram or cylinder, and having non-return valves in itsinlet and outlet ports, with means for holding at least one of thevalves open, to drain the pump when it is removed from the container,suchas a stop at the end of the valve stem which is spring biassed tohold the valve closed.

It is preferred also that the discharge passage includes a dischargeduct formed in a rigid ducted block connected to the other side of thesupport member referred to above and terminating at the said dischargenozzle or opening. In any case the ducted block and nozzle, if fitted,preferably include auxiliary heater means arranged to increase thetemperature of the molten metal. Ideally, in this case, the dischargeduct will be a relatively massive metal casting which can act as athermal reservoir.

In a particular preferred construction according to the invention thedischarge passage is inclined upwards to the discharge nozzle or openingto assist in the removal of any air trapped in the passage. Ideally thedischarge passage will terminate in a pouring lip or weir at thedischarge nozzle or opening to assist in removing any air trapped in thepassage, the arrangement being such that at the end of a pouringoperation molten metal is retained in and substantially fills thedischarge passages.

The invention may be performed in various ways and one specificembodiment with certain possible modifications will now be described byway of example with reference to the accompanying drawings, in which:

FIG. 1 is a somewhat diagrammatic vertical crosssection illustrating themain components of the pouring system,

FIG. 2 is a vertical cross-section view on the line IIII in FIG. 1,

FIG. 3 is a horizontal cross-section through the pouring head on theline [IIII] of FIG. I, and

FIG. 4 is an enlarged fragmentary side view of the mounting arrangementfor the pump shown in FIG. 1.

Referring first to FIG. 1, the apparatus comprises basically a generallyrectangular metal melting pot or container 10 provided with internalelectrical heating coils 49. This container 10 is mounted at an elevatedposition on an automatic casting machine, so as to discharge molten leadinto moulds moved in sequence by an endless conveyor below a pouringno'zzle. Secured to one side wall 11 of the container, by welding, is anaccurately positioned mounting block 12, the block having two, generallyvertical, opposed faces, which are inclined from the vertical at a smallangle of about 2.

Directly mounted on this support block 12 is a pump unit 13 comprising amain metal body or casting having at its lower end apump cylinder orbore 14 containing a reciprocating piston 15 attached to a pneumaticactuating ram 19 mounted above the pump body. The bottom end of the pumpcasting is closed by a plate 16 with cooperating inlet and outletpassages 21,22 respectively, fitted with non-return poppet-type inletand exhaust valves 23,24 respectively, each attached to sliding stems 50which extend upwards through drillings in the block and have manuallycontrolled knobs 51 at their upper ends, and are surrounded by springs52 which tend to hold both valves closed. By depressing the knobs boththe valves can be opened. The pneumatic ram 19 contains adjustable limitstops 19A for determining the stroke of the pump and thus the volume ofmetal supplied. This may also be achieved by an adjustable link 15A inthe valve stem.

Since the valves are positioned at the bottom of the pump body, thisensures that they can be maintained in a continually submerged state sothat they do not become subjected to oxidation. It should also be notedthat removal of the plate 16 enables direct access to the pump chamber,both valves 23,24 andthe inlet and outlet passages 21,22, so that theycan easily be inspected and maintained.

livery nozzle unit 26. The unit 25 comprises a massive generallycylindrical metal casting 28 with a central passage 29. The whole lengthof this casting is surrounded by electric heaters 27 shrouded in aninsulating cover 30. At the near end the casting 28 has a reduced neck31 and a flange 32 provided with throughdrilling 33 to'receive bolts 37by which it is secured to the supporting block 12 and the pump unit 13(see FIGS. 2 and 4). These bolts 37 are positioned well above the liquidmetal level so as not to be attacked by the liquid metal and so as to bereadily accessible. At the other end the casting has a recess 34 fromwhich drillings extend to the adjacent end face to receive furthermounting bolts for securing the pouring nozzle unit 26'. The abuttingsurfaces of the pump unit 13, the support block 12, the discharge unit25 and the nozzle unit are ground flat so that there will be no seepageand good physical contact between all these parts and a good contactarea, relative to the size of the passage 29, thus providing good heattransfer properties.

The pouring nozzle 26 comprises a casting 35 having a central inlet 36on its rear face to communicate with thecentral passage 29 in thecasting 28, this port 36 opening into a horizontal gallery 38 from whichlead two main horizontal outlet slots 40 (see FIG. 3). The surface oftheinclined front face 42 of the member 35 is relieved above eachslot 40as shown at 43, and to this inclined front face 42 is secured a coverplate 44 having a number of inclined delivery slots 45 which liegenerally vertical when this plate is secured to the member 45. When theplate 44 is secured in position it provides a lip or weir 47. above thelevel of the top surface of the gallery 38. It will also be noted thatthe whole discharge assembly including the two units 25 and26 is mountedon the support block 12 so that the centre line of the flow passage isinclined upwards towards the discharge openings at a small angle ofabout 2.This assists in movement ofany air along the passage with themolten metal. The combination of the lip 47 with the terminal verticaldischarge slots 45 prevents the molten metal issuing with excessivevelocity, and so reduces spillage. Also the small area of molten liquidat the lip 47 between pourings is relatively small so that littleoxidation occurs. Electric heater units 39 are provided within bores inthe nozzle 26 and the nozzle is insulated by a jacket 41.

In use the pneumatic ram 19 is controlled automatically in relation tothe stepping movements of the conveyor, and the ram and pump unit 13 areso designed and controlled that an accurate metered volume of moltenmetal is delivered at each stroke to fill the particular moulds in use.The temperature of the metal in the melting pot may be about 300 -350 C,which is sufficient tomaintain the metal in a fluid state for pumpingout below the required pouring temperature ofabout 500 C. By keeping thetemperature below this final figure oxidisation in the pot is reduced.The auxiliary heaters 27 and 41 in the units 25 and 26 progressivelyraise the temperature of the metal to about 500 C at the pouring lip.Thus, only the metal at the outlet of the nozzle unit 26 will havereached the pouring temperature. The use of a massive metal casting 28acts as a thermal reservoir so that the temperature of the metal can beraised rapidly during its passage through the relatively short centraldrilling 29.

The container 10 is provided with an air tight lid 53 so that an inertgas (such as nitrogen) may be introduced into the container 10 throughgas inlet 54. This provides a means of reducing or eliminating oxidationof the molten metal. Further metal for melting can be introduced throughthe hatch 55. The lid 53 fits around the pump unit 13 and can easily beremoved to provide access to the pump unit for replacement ormaintenance.

If and when the pump 13 requires maintenance, as is to be expected underthe conditions experienced, it is relatively simple to dismount and ifnecessary replace the pump without shutting down the system or drainingthe melting pot. The mounting bolts 37 holding the pump body to thesupport block 12 are freed, and the whole pump unit is simply lifted outof the pot, the valves being opened by pressing down the knobs on thevalve stems to allow all the molten metal to drain off. No further partshave to be removed and a fresh pump can be substituted very rapidly. Incarrying out maintenance on the pump itself, the working parts arereadily accessible by removing the plate 16. Likewise if problems arisein the discharge unit 25 or the delivery nozzle 26 one or both parts canreadily be removed and replaced without closing down thesystem.

Various modifications may be made to the design and construction of theapparatus shown in the drawings, within the scope of the invention, asclaimed herein. Thus, the melting pot 10 can be shaped other thanrectangular, such as circular. Also, the mounting block 12 can besecured to the melting pot by means other than welding, such as bybolting the block to the wall 11. Furthermore, the angle subtended tothe horizontal by the flow passage, can be other than 2, as desired.

I claim:

1. Apparatus for discharging of a molten metal such as lead, comprisinga melting pot, heating means associated with the melting pot to maintainthe metal in a molten state, a pump mounted at least partly within themelting pot, the pump having an inlet near the bottom of the meltingpot, and valve means to allow flow only in a discharge direction, asupport member, integral with the melting pot providing a physicalmounting for the pump, a discharge passage defined to lead from thesupport member, a pump passage defined in the pump, cooperating with thedischarge passage to provide a path for the discharge of molten metalfrom the pump, a discharge opening being provided at the outlet of saidpath, and mounting means for releasably mounting the pump on the supportmember together with means for holding the valve means open to enablethe pump to be drained when it is removed from the melting pot, beingprovided, so that the pump can be readily demounted from the supportmember and drained for maintenance or replacement.

2. Apparatus according to claim 1, in which the pump is a reciprocatingpiston pump actuated by a fluid operated ram, and having inlet andoutlet ports, the valve means comprising non-return valves provided forthe inlet and outlet ports.

3. Apparatus according to.claim 2, in which the valve has a valve stemand the means for holding the valve means open comprises a stop at theend of the valve stem and spring biassing means for holding the valveclosed.

4. Apparatus according to claim 2 wherein the pump is a positivedisplacement pump having variable characteristics whereby a metered, butvariable, quantity of molten metal may be delivered on each stroke ofthe piston.

5. Apparatus according to claim 1, including a rigid block, having adischarge duct, wherein the discharge passage includes the dischargeduct, mounting means corrects the rigid block to the side of the saidsupport member opposite to the pump, and the discharge duct terminatesat the said discharge opening.

6. Apparatus according to claim 5 wherein the abutting surfaces of thepump, support member and rigid block are ground flat to avoid seepage,and provide a good contact area and heat transfer properties.

7. Apparatus according to claim 6, in which auxiliary heater means arearranged in association with the ducted block to increase thetemperature of the molten metal.

8. Apparatus according to claim 5, in which the ducted block is arelatively massive metal casting which can act as a thermal reservoir.

9. Apparatus according to claim 5, in which the discharge passage isinclined upwards to the discharge opening to assist in removing any airtrapped in the passage.

10. Apparatus according to claim 1, in which a pouring lip is formed atthe termination of the discharge passage, so arranged that, at the endof a pouring operation, molten metal is retained in and substantiallyfills the discharge passage.

11. Apparatus according to claim 1, in which the discharge opening is inthe form of at least two slots.

12. Apparatus according to claim 1, in which an inclined front face isformed on that part of the apparatus where the discharge passageterminates, and the discharge opening is formed on that inclined frontface.

13. Apparatus according to claim 12, in which a cover plate having anumber of inclined delivery slots is provided over the dischargeopening, so that the slots will lie generally vertical when the coverplate is secured to the said inclined front face.

14. Apparatus according to claim 1, in which a discharge nozzle isprovided at said discharge opening.

1. Apparatus for discharging of a molten metal such as lead, comprisinga melting pot, heating means associated with the melting pot to maintainthe metal in a molten state, a pump mounted at least partly within themelting pot, the pump having an inlet near the bottom of the meltingpot, and valve means to allow flow only in a discharge direction, asupport member, integral with the melting pot providing a physicalmounting for the pump, a discharge passage defined to lead from thesupport member, a pump passage defined in the pump, cooperating with thedischarge passage to provide a path for the discharge of molten metalfrom the pump, a discharge opening being provided at the outlet of saidpath, and mounting means for releasably mounting the pump on the supportmember together with means for holding the valve means open to enablethe pump to be drained when it is removed from the melting pot, beingprovided, so that the pump can be readily demounted from the supportmember and drained for maintenance or replacement.
 2. Apparatusaccording to claim 1, in which the pump is a reciprocating piston pumpactuated by a fluid operated ram, and having inlet and outlet ports, thevalve means comprising non-return valves provided for the inlet andoutlet ports.
 3. Apparatus according to claim 2, in which the valve hasa valve stem and the means for holding the valve means open comprises astop at the end of the valve stem and spring biassing means for holdingthe valve closed.
 4. Apparatus according to claim 2 wherein the pump isa positive displacement pump having variable characteristics whereby ametered, but variable, quantity of molten metal may be delivered on eachstroke of the piston.
 5. Apparatus according to claim 1, including arigid block, having a discharge duct, wherein the discharge passageincludes the discharge duct, mounting means corrects the rigid block tothe side of the said support member opposite to the pump, and thedischarge duct terminates at the said discharge opening.
 6. Apparatusaccording to claim 5 wherein the abutting surfaces of the pump, supportmember and rigid block are ground flat to avoid seepage, and provide agood contact area and heat transfer properties.
 7. Apparatus accordingto claim 6, in which auxiliary heater means are arranged in associationwith the ducted block to increase the temperature of the molten metal.8. Apparatus according to claim 5, in which the ducted block is arelatively massive metal casting which can act as a thermal reservoir.9. Apparatus according to claim 5, in which the discharge passage isinclined upwards to the discharge opening to assist in removing any airtrapped in the passage.
 10. Apparatus according to claim 1, in which apouring lip is formed at the termination of tHe discharge passage, soarranged that, at the end of a pouring operation, molten metal isretained in and substantially fills the dis-charge passage. 11.Apparatus according to claim 1, in which the discharge opening is in theform of at least two slots.
 12. Apparatus according to claim 1, in whichan inclined front face is formed on that part of the apparatus where thedischarge passage terminates, and the discharge opening is formed onthat inclined front face.
 13. Apparatus according to claim 12, in whicha cover plate having a number of inclined delivery slots is providedover the discharge opening, so that the slots will lie generallyvertical when the cover plate is secured to the said inclined frontface.
 14. Apparatus according to claim 1, in which a discharge nozzle isprovided at said discharge opening.